code: def init_plot_data(self):
      ax = self.fig.add_subplot()
  
      x = np.arange(120.0) * 2 * np.pi / 60.0
      y = np.arange(100.0) * 2 * np.pi / 50.0
      self.x, self.y = np.meshgrid(x, y)
      z = np.sin(self.x) + np.cos(self.y)
      self.im = ax.imshow(z, cmap=cm.RdBu, origin="lower")
  
      zmax = np.max(z) - ERR_TOL
      ymax_i, xmax_i = np.nonzero(z >= zmax)
      if self.im.origin == "upper":
          ymax_i = z.shape[0] - ymax_i
      self.lines = ax.plot(xmax_i, ymax_i, "ko")
  
      self.toolbar.update()
  
file_path: matplotlib/galleries/examples/user_interfaces/embedding_in_wx3_sgskip.py
imports: import wx
  import wx.xrc
  import numpy
  from matplotlib.backends.backend_wxagg import FigureCanvasWxAgg
  from matplotlib.backends.backend_wxagg import NavigationToolbar2WxAgg
  import matplotlib.cbook
  import matplotlib.cm
  from matplotlib.figure import Figure
label_desc: Use image node_id 2 for calling the PlotPanel obj's underlying member method code with example usage: obj.init_plot_data() without return types